Carl is Rick's seven-year-old son. He speaks with the tactless honesty of a seven-year-old, like when he tells Olivia, "Ain't your daddy dead?" (332) as though she forgot, and later, when hunting, he says "We don't have to get as much [food] as usual, dad. Amy's dead… and Jim's too sick to eat" (675). Well, the kid has a point.
When Rick decides to teach everyone to wield a gun, he means everyone (well, except the female child Carl's age and the toddlers), including young Carl. Rick assures everyone that Carl will keep his gun "holstered at all times" (550). Whew. That's a relief. Kids are so good at following directions. No one except Carl's mom seems to care. We guess seven-year-olds with handguns aren't an unusual sight in zombie invasion situations.
Carl's responsible with the gun, only shooting a zombie and saving his mother in the ultimate "told ya so" moment. By the end of chapter one, he's transformed into a little mini-me of his dad. He's wielding a gun and wearing his dad's hat. While hunting zombies is scary, it feels kind of like hunting. They're not really human, after all. But that changes when Carl shoots Shane, who's 100% human, after Shane threatens his dad. The final scene involves Carl crying, saying "It's not the same as killing the dead ones, daddy" (760). In the end, he's still a little kid.